Long quantum channels for high-quality entanglement transfer

Leonardo Banchi; Tony John George Apollaro; Alessandro Cuccoli; Ruggero Vaia; Paola Verrucchi

doi:10.1088/1367-2630/13/12/123006

paper

Long quantum channels for high-quality entanglement transfer

arXiv:1105.6058 · doi:10.1088/1367-2630/13/12/123006

Abstract

High-quality quantum-state and entanglement transfer can be achieved in an unmodulated spin bus operating in the ballistic regime, which occurs when the endpoint qubits A and B are coupled to the chain by an exchange interaction $j_{0}$ comparable with the intrachain exchange. Indeed, the transition amplitude characterizing the transfer quality exhibits a maximum for a finite optimal value $j_{0}^{o pt} (N)$ , where $N$ is the channel length. We show that $j_{0}^{o pt} (N)$ scales as $N^{- 1/6}$ for large $N$ and that it ensures a high-quality entanglement transfer even in the limit of arbitrarily long channels, almost independently of the channel initialization. For instance, the average quantum-state transmission fidelity exceeds 90% for any chain length. We emphasize that, taking the reverse point of view, should $j_{0}$ be experimentally constrained, high-quality transfer can still be obtained by adjusting the channel length to its optimal value.

12 pages, 9 figures

Long quantum channels for high-quality entanglement transfer

Abstract

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